An expansion joint is formed by purposely providing an opening or gap between adjoining structural members for accommodating dimensional changes to the gap occurring as expansion and contraction due to temperature changes and/or seismic cycling and vibration.
An expansion joint cover assembly is placed over the expansion joint gap to prevent the ingress of debris and water into the gap and to provide a smooth transition for pedestrian and vehicular traffic across the expansion joint gap. The expansion joint may be damaged by the ingress of debris and water but, also by abrasion and compression forces generated by the passage of motorized vehicular traffic across the expansion joint gap.
Elongated metal plates placed in an end-to-end relationship have been secured to concrete structural members in an attempt to protect the expansion joint from damage due to pedestrian and vehicular traffic. The metal plates often become deformed and do not form a uniform seated engagement with concrete structures, particularly where the traffic bearing upper surfaces of the adjacent concrete structures are irregular or undulating and therefore fail to provide the necessary uniform planar support for the metal plates. Under these conditions, the metal plates may be bent and distorted due to impact loading of traffic and acquire a state of looseness about their mounting bolts which degrades further when the mounting bolts bend or break.
Known expansion joint cover assemblies include spacing mechanisms that attempt to stabilize the cover plates in a centered or default position across the expansion joint gap. These spacing and realignment mechanisms stabilize the cover plates by adding mass, as well as by utilizing members engaged with the cover plate itself to facilitate return of the cover plate to its default position deformation to the expansion joint caused by seismic cycling and vibration, thermal cycling, or traffic.
A need still exists in the art for an improved expansion joint cover plate assembly including an improved swing arm equidistance system that (1) does not corrode, (2) provides a pretensioned spring force on the cover plate of the assembly, (3) is easy to install, (4) is easily replaceable, (5) allows the cover plate to accommodate slab differential movements, (6) is rigid enough to prevent excessive cover plate bouncing and misalignment, and (7) is cost effective. There is also a need to provide improved means of installation that reduces the difficulties of blindly installing the expansion joint cover plate assembly within an expansion joint gap.